Heat-treating furnace



Oct. 17, 1944. w "E JOHNS-[0N l 2,360,348

HEAT TREATING FURNACE Filed May 1o, 1943 2 sheets-sheet 1 g sheets-sheet 2 W. E. JOHNSTON HEAT TREATING FU'RNACE Filed May 10, 1943 Oct. '17, 1944.

,Inv-etor WAYBURN E. JOHNSTON ttornz Fig: 3.

Patented Oct. 17, 1944 UNITED-STATES PATENT OFFICE HEAT-TREATIN G FURNACE Wayburn E. Johnston, Minneapolis, Minn.

Application May 10, 1943, Serial No. 486,298

7 Claims.

This invention relates to a heat treating furnace. Such furnaces are used for annealing and otherwise heat treating castings and other articles. It has been common practice to have such furnaces with a rotating platform at the bottom, said furnaces having a chamber above said platform into which the heating medium, usually heated air or gases, was delivered. Said chambers have customarily had a side wall and an outlet passage located in said side wall. The heated air or other gases pass as much as possible into contact with the articles to be heated or treated.

It is an object of this invention to so construct a furnace that the heat from the gases will be efficiently used and a large part of the same transferred to the articles to be heated.

It is a further object of the invention to provide a heat treating furnace having a chamber and surrounding wall, means for delivering the heating medium through said wall, a rotating platform at the bottom of said chamber for supporting the articles to be heated, said chamber having a vent or outlet passage extending to adjacent the bottom thereof whereby said heating medium must pass downwardly to a point adjacent said platform before passing out at said outlet passage.

It is further an object of the invention to provide a heat treating furnace having a surrounding wall which may be cylindrical, means for delivering the heating medium into said chamber through said wall, a rotatable platform at the bottom of said chamber, said chamber having a vent or outlet passage substantially at the center thereof which extends to a point adjacent said platform whereby said heating medium will be caused to move downwardly adjacent said platform and into contact with the articles to be heated before reaching and passing out at said vent or outlet passage.

It is more specifically an object of the invention to provide such a heat treating furnace as set forth in the preceding paragraph in which said chamber has a roof which extends downwardly in an inclined direction toward said outlet passage.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawings in which like reference characters refer to similar parts throughout the several views and in which:

Fig. 1 is a central vertical section through a heat treating furnace embodying the present instructed of metal.

vention taken substantially on line of Fig. 2 as indicated by the arrows;

Fig. 2 is a horizontal section taken substantially on line 2 2 of Fig. 1; and

Fig. 3 is a partial section similar to Fig. 1, shown on an enlarged scale and also of modified construction,

Referring to the drawings a heat treating furnace is shown having a vertical wall I0 which surrounds a chamber I 0a and while this wall may be of various forms or shapes, in the embodiment of the invention illustrated it is shown as cylindrical. Wall I0 is shown as having an inner portion |01) which will be made of some insulating and heat resisting material and as having an outer shell |0c which will preferably be con- Wall I0 is shown as having extending therethrough openings or passages |0d. Said wall has specially constructed inserts or members Ille surrounding openings Id which are made of higher heat resisting or refractory material. Openings I0e are shown as having smaller inlet portions I 0f and portions I0e are covered at the outer side with suitable metal plates I0g. Certain apparatus will be installed adjacent openings Illd and directed therein for delivering fuel and air to produce hot gases or products of combustion to be delivered into chamber Illa. More than two openings for the heating medium are sometimes used and in such cases they would be disposed substantially on the lines |022 shown in Fig. 2. Such apparatus is Well known and common in the art and need not further be described. It will be noted that the openings Illd are offset circumferentially at opposite sides of a diameter drawn therebetween to cause the gases in chamber Illa to rotate `usually in the same direction as the table. Wall |0 is also provided with door openings |0h, and |01' for the introduction of and the removal of the articles to be treated. Said openings |011, and |01' are closed by movable doors Il and I2. Suitable members I3 and I4 are provided as necessary to guide doors II and I2 in their movement. While said doors may be variously moved and operated, in Fig. 1 one of the doors I2 is shown as having a chain I4 secured to its upper end which will be 'connected to some operating means for raising and lowering said door to expose and close openings |01. Chamber |0a has a roof |01 which will also be formed of some heat resisting and insulating material. Wall |07 is shown as extending substantially horizontally. Chamber I0a is provided with an outlet or vent passage |0lc which extends vertically and is illustrated as disposed substantially at the center of chamber Illa. Passage |016 extends vertically and is lined with some heat resisting and insulating material Illm. From the bottom of outlet passage Ilc in the specific embodiment of the invention illustrated, the wall of chamber Illa extends outwardly and upwardly to top wall |07, thus being of depending or inverted frustoconical shape- The frustoconical or inclined portion I 011, of the wall will also be formed of similar material as portions |01) and |071 While portion |011, could be variously constructed, in the embodiment of the invention illustrated it is shown as made of courses of blocks or similar members supported on circular angle bars I6 secured to and supported by brackets Il which in turn are secured to and supported by upwardly and outwardly extending circumferentially spaced bars I8. Bars I8 are at their upper ends secured to horizontally extending I-beams I9. Beams I9 are connected by radially spaced circumferentially extending smaller beams. Beams I9 will be supported at their outer ends on the metallic portions of casing IIlc as shown in Fig. l, and are also secured at their inner ends to transversely extending larger I-beams 22 which will extend transversely of the furnace and be supported on the wall at opposite sides thereof. Bars 23 extend vertically about the material of outlet passage I07c and are secured at their lower ends to brackets 24 to which members I8 are also secured. A shell 2I extends about material Illm being supported on bars 23. Brackets 24 support hanger plates 28 which form the support for the lower portion of material Illm and wall portion IML. The bottom of the outer wall IIJ is provided With a metal ring 30 to which is attached an angle 3| having a vertical side extending downwardly and adapted to be disposed in a body of sand or similar material 32. Ring 30 and the casing IIlc of wall I0 are supported upon heavy metal brackets 29 forming the base support for wall I0. Said sand is carried in a trough 33 secured to the outer side of a circular casing 34 carried on radially extending beams 35 forming the support for a table or platform 36 which forms the bottom of chamber Illa. While table 36 and its support'could be variously formed, in the embodiment of the invention shown in Fig. l, beams 35l are shown as extending to a central member 31 secured to a member 38 having i a flange surrounding the upstanding cylindrical portion of a pedestal or central bracket 39. An I-beam 40 of sectional form and of substantially circular shape supports beams 35 by means of suitable brackets 4I and said beam 46 at its bottom carries a cylindrical track member 42. Track 42 bears at its bottom upon circumferentially spaced rollers 43 carried in suitably spaced brackets 44 which support the platform structure. One of the rollers 43 has secured thereto a shaft 45 which will be connected to some suitable driving means so that track 42 and thus table 36 will be rotated. Table 36 will be made of some suitable heat resisting and insulating material and the same is shown as having a surrounding ring 36h. A plate 36a is disposed loosely between table 36 and beams 35. This gives flexibility for expan sion due to the heating of the parts.

In Fig.3 a table or platform 56 is shown similar to table or platform 36, the same having an outer ring 56h. Ring 56h rests upon a bottom plate 56a which in turn rests loosely upon a cylindrical frame supporting member 6I. Frame 6I has spaced annular portions 6Ia and has secured thereto at its center a bearing member 6I b having a flange Slc of depending annular form which surrounds a pedestal member 58 resting upon a foundation structure 59. A bearing plate 66 is disposed between member 6Ic and pedestal bracket 58. Member 6I carries a bottom bearing plate 62 supported upon circumferentially spaced rollers 63 carried in suitable bearing brackets 64 in turn secured to base brackets 65 seated upon suitable foundation structures 66. One of the rollers 63 will be driven so that table 56 will be rotated. Trough 3l is shown as secured to the outer side of member 6I by circumferentially spaced bolts 61.

In operation the castings or other articles 'I0 to be treated will be placed on table 36 as indicated in dotted lines in Fig. 1. These articles are customarily loaded onto the table through the door opening Ih and after the table has rotated through the desired period they will be unloaded from the table through door opening IIl. The doors II and l2 will be suitably operated for such loading and unloading operations. Table 36 will be rotated by the driving roller and will rotate slowly, the same being supported upon rollers 43 or 63. The hot air, gases or products of combustion used for treating the articles 'I0 will be delivered through openings lud. The disposition of openings Id in their offset relation as described, tends to cause a whirling movement of the gases in chamber Illa. As the gases are successively delivered they move downwardly in chamber I 0a and will move toward the center thereof to reach the outlet or vent passage Ilc. The location of the opening of vent passage lek adjacent table 36 insures that gases must reach a low point adjacent the table before being Vented or before passing out of chamber Ia. It will thus be seen that the gases move downwardly and engage the articles 10 and then move inwardly, the same being deflected downwardly by the inclined surface of wall portion i011 until they nally reach and pass out through the opening or passage I'Illc. The hottest gases are brought into contact with the articles 'I0 and the gases are gradually cooled as they move downwardly and inwardly and thus the gases are vented at their lowest temperature. In furnaces of the prior art where the outlet or vent passage was at the top or in the side walls Ib diiculty was experienced in making the gases move downwardly and properly contact the articles supported upon the table. With the present construction the gases as stated, are delivered tangentially from the burners or other delivery means and follow the outside of the chamber first, gradually moving downwardly and traveling across the lower portion of the chamber to the vent. Rapid motion of the gases speeds up the heating and treating of the articles. The gases are thus effectively brought into contact with the articles 'I6 and the heat of the gases is effectively transferred thereto.

From the above description it will be seen that I have provided a very simple and efhcient eonstruction of furnace and one which will result in much more eicient use of the heat and much more eiective treatment of the articles treated. The furnace can be built in any desired size or from about six foot table diameter to a table diameter of about 30 feet, which is the usual range in the art of such rotating table furnaces. The invention broadly deals with having the gases circulated in the h-eating chamber and then being brought to a point adjacent the bottom of the chamber before being vented so as to most effectively engage the articles to be treated. Obviously the invention is not limited to any particular type of furnace. It will be apparent that the invention will have a high degree of utility for the purpose intended.

It will of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts, without departing from the scope of applicants invention, which generally stated, consists in a device capable of carrying out the objects above set forth, in the parts and combinations of parts disclosed and dened in the appended claims.

What is claimed is:

l. A heat treating furnace comprising a heating chamber having a surrounding wall, means for directing a heating medium into said chamber through said wall, a platform at the bottom of said chamber for supporting articles to be treated and movable relatively to said wall, said chamber having its greatest height adjacent said wall and having a vent passage for said medium Within said chamber and extending to adjacent said platform whereby said gases must pass close to said platform and into engagement with said articles before passing to said vent passage.

2. A heat treating furnace comprising a heating chamber having a surrounding Wall, means for directing a heating medium into said chamber through said wall, a platform at the bottom of said chamber for supporting articles to be treated and movable relatively to said wall, said chamber having a central Vent or outlet passage for said medium having its lower end disposed adjacent said platform whereby said medium must pass to a point adjacent said platform before reaching said outlet passage.

3. A heat treating furnace comprising a heating chamber having a substantially cylindrical wall, means for directing a heating medium into said chamber through said wall, a platform at the bottom of said chamber revoluble about a central axis for supporting articles to be treated,

said chamber having an outlet passage substantially at the center thereof, the lower end of which is disposed adjacent said platform, said chamber having a top wall, a portion of which extends downwardly in an inclined direction toward the bottom of said outlet passage.

4. The structure set forth in claim 3, said portion being of frusto conical shape and surrounding said outlet passage.

5. A heat treating furnace comprising a heating chamber having a substantially cylindrical wall, means for directing a heating medium into said chamber through said wall at opposite sides thereof, said means being offset at opposite sides of a diameter extending therebetween, a platform at the bottom of said chamber revoluble about a central axis for supporting articles to be treated, said chamber having an outlet passage substantially at the center thereof having its lower end disposed adjacent said platform and extending upwardly therefrom, said chamber having a top wall which is of inverted frusto-conical shape at its central portion, said wall thus extending downwardly toward said outlet passage.

6. A heat treating furnace comprising a heating chamber having a wall extending around the same, a platform at the bottom of said chamber revoluble relatively to said wall, a vent passage within said chamber having an inlet opening adjacent said platform and leading from said chamber and means for delivering a heated medium into said chamber through said wall located well above said inlet opening whereby said medium must pass downwardly toward said platform to enter said inlet opening.

'7. A heat treating furnace comprising a heating chamber having a wall extending thereabout, a vent passage surrounded by said chamber, said passage having an inlet opening, a platform at the bottom of said chamber, said inlet opening being disposed adjacent said platform and means for directing a heating medium into said chamber through said wall above said inlet opening. WAYBURN E. JOHNSTON. 

